The present invention relates generally to supplemental inflatable restraint (air bag) systems and more particularly to a hybrid inflator.
A hybrid inflator comprises a pressure vessel into which is stored a quantity of inert, pressurized gas. Means are provided to selectively open a passage leading from the pressure vessel to exit ports to permit the egress of the inflation gas. Such means typically includes a mechanism for braking a rupturable disk. Hybrid inflators may also include heat generators, such as a quantity of propellent, to heat the gas remaining in the pressure vessel thereby achieving a more efficient inflation of the air bag. It is a requirement that the orientation of the exit ports be arranged to maintain the hybrid inflator in a thrust neutral condition when gases exit the inflator and specifically when the inflator is not part of an air bag module. By thrust neutral it is meant that when gas exits the exit ports the resultant of the reaction forces is essentially zero. As can be appreciated, if the hybrid inflator were not thrust neutral and is accidentally energized or gas is discharged, such as from an over pressurization due to fire, etc., the inflator could be propelled about due to the non-zero resultant forces generated by the exiting gas flow.
As such, the above thrust neutral requirement is beneficial when the hybrid inflator is being carried, shipped, etc. However, the above requirement, as will be seen below, reduces the efficiency of the air bag inflation process. Accordingly, the invention comprises: an air bag module comprising: an inflator for generating inflation gas; an air bag disposed about the inflator to receive the inflation gas exiting the inflator; a structure for supporting at least the inflator. The inflator comprising: a pressure vessel and a plurality of exit ports through which inflation gas exits the inflator. The exit ports are arranged to render the inflator in a thrust neutral condition when the inflator is not attached to the structure. The module comprising first means for closing a designated set of exit ports to render the inflator in a non-thrust neutral condition when supported by the structure. The first means includes a plug received in each of the designated exit ports. Each plug is preferably received though a portion of the structure such that if the inflator is removed from the structure each plug must also be removed, thereby opening all of the previously closed exit ports and rendering the inflation in its thrust neutral condition once again.
Many other objects and purposes of the invention will be clear from the following detailed description of the drawings.